The north side was dominated in the 1800s by the General Mining Association (GMA), which had been formed in the 1820s after the Colony of Cape Breton Island was amalgamated back into Nova Scotia.

Several independent collieries opened on the south side and by the 1870s, Canada's federal government had implemented its National Policy of economic protectionist measures.

The Whitney syndicate was offered an unprecedented 99-year lease on a fixed royalty; the group exercised its options, acquiring most of the existing bituminous coal mines in eastern Cape Breton and co-opting such local figures as John Stewart McLennan and David MacKeen.

There were, however, costly mistakes, prominent among them the tendency to become locked into low-price contracts (such as to Whitney's companies), thus missing a large market at higher prices.

The company made a large public offering of stock, which tumbled in price when Whitney failed to get the American import duty on coal removed or at least reduced.

Whitney expanded operations at Sydney with the organization in March 1899 of the Dominion Iron & Steel Company Ltd. (DISCO), which had funding in both Canada and the United States.

The promise of federal bounties, together with concessions from the Liberal provincial administration of Premier George Henry Murray, enabled DISCO to begin work in June 1899 on the largest integrated steel mill in the British Empire.

Located on the south side of Sydney Harbour, which Whitney said offered more advantages to steel making than anywhere else in the world, the mill was completed in 1901.

The fall-out from World War I saw a syndicate of British investors led by Montreal, Quebec industrialist Roy M. Wolvin negotiate a takeover of Dominion Steel Corporation from Plummer in 1919.

As a result, BESCO's investors pressured management to force many difficult working conditions in order to achieve higher production from its workforce.

BESCO subsidiary DISCO (the steel mill) fell into receivership in the spring of 1926 after short-term financing was refused; this would eventually lead to the break-up of the conglomerate.

The company's fortunes were boosted by World War II with its control of manufacturing and their inputs and at one point DOSCO was the largest private employer in the nation.

By the early 1960s DOSCO was in a continuous slide and sought to halt its decline by shutting various poorly performing mines in the Pictou and Sydney coal fields; from 9 in 1960 to 5 in 1965.

In 1965, DOSCO announced that its remaining mines had only 15 years of production left and it would not undertake any further capital expenditures and would exit the industry within months.

The vast public outcry to DOSCO's announcement in Industrial Cape Breton saw the minority government of Prime Minister Lester Pearson come under incredible political pressure to resolve the crisis.